Microscopy imaging applications involving light field microscopes and/or cameras, video cameras, telescopes and more have generally been limited in their ability to obtain image data from subjects. That is, most imaging devices do not record most of the information about light distribution entering the device. For example, conventional microscopes do not record most of the information about the light distribution entering from the world. In these devices, collected light is often not amenable to manipulation for a variety of approaches, such as for focusing at different depths (distances from the imaging device), correcting for lens aberrations or manipulating an angle of view.
Many imaging applications suffer from aberrations with the equipment (lenses) used to collect light. Such aberrations may include, for example, spherical aberration, chromatic aberration, distortion, curvature of the light field, oblique astigmatism and coma. Correction for aberrations has typically involved the use of corrective optics, which tend to add bulk, expense and weight to imaging devices. In some applications benefiting from small-scale optics, the physical limitations associated with the applications make it undesirable to include additional optics.
Microscopes are the primary scientific instrument in many biological laboratories. In a transmission-mode light microscope, an illumination source is focused by a condenser lens (for illumination) onto a specimen. An objective lens magnifies the specimen, creating a real image at an intermediate image plane. In more traditional microscopes, the intermediate image plane is located inside the microscope tube, and ocular (eyepiece) further magnifies a portion of this image, thereby creating a second image that is focused at infinity. Although the performance of microscopes, and their ease of use, has improved dramatically over their 400-year history, microscopes suffer from several limitations. First, diffraction limits their spatial resolution, especially at high magnification. This limit can be ameliorated by enlarging the lens opening (called the numerical aperture) while keeping the lens strongly curved, but we reach a practical limit when the lens becomes a half-sphere. Second, in a microscope, objects are seen in orthographic projection from a single direction. Moving the specimen laterally on the microscope stage does not produce parallax, making it hard to disambiguate superimposed features. Third, microscopes have a very shallow depth of field, particularly at high magnification and numerical apertures. This “optical sectioning” is useful when viewing thick specimens, but examining the entire specimen requires moving the stage up and down, which is slow and may not be possible on live or light-sensitive specimens.
Difficulties associated with the above have presented challenges to microscopy imaging applications, including those involving the acquisition and altering of digital images.